Java Mocking入门—使用Mockito
我们都会编写单元测试程序,但我们当前所面临的挑战是被测单元可能依赖于其他组件。而对于单元测试配置其他组件,绝对是过枉矫正。相反,我们可以使用Mocks框架代替其他组件,继续进行单元测试。
为了展现如何使用mock框架,我编写一个数据访问层(DAL),该类对应用提供了一套API 接口来访问和修改数据库中的数据。之后在不需要连接数据库的情况下,对DAL类进行单元测试。数据库可以是本地数据库、远程数据库、文件系统或者任何可以储存和检索数据的地方。使用DAL类帮助我们 将数据映射操作从应用代码中分离出来。
使用maven建立一个Java工程。
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mvn archetype:generate -DgroupId=info.sanaulla -DartifactId=MockitoDemo -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=
false
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以上操作建立了一个MockitoDemo文件夹,然后创建源文件和测试文件的整个目录结构。
考虑下面这个示例模型类:
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package
info.sanaulla.models;
import
java.util.List;
/**
* Model class for the book details.
*/
public
class
Book {
private
String isbn;
private
String title;
private
List<String> authors;
private
String publication;
private
Integer yearOfPublication;
private
Integer numberOfPages;
private
String image;
public
Book(String isbn,
String title,
List<String> authors,
String publication,
Integer yearOfPublication,
Integer numberOfPages,
String image){
this
.isbn = isbn;
this
.title = title;
this
.authors = authors;
this
.publication = publication;
this
.yearOfPublication = yearOfPublication;
this
.numberOfPages = numberOfPages;
this
.image = image;
}
public
String getIsbn() {
return
isbn;
}
public
String getTitle() {
return
title;
}
public
List<String> getAuthors() {
return
authors;
}
public
String getPublication() {
return
publication;
}
public
Integer getYearOfPublication() {
return
yearOfPublication;
}
public
Integer getNumberOfPages() {
return
numberOfPages;
}
public
String getImage() {
return
image;
}
}
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操作Book模型类的DAL类:
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package
info.sanaulla.dal;
import
info.sanaulla.models.Book;
import
java.util.ArrayList;
import
java.util.Arrays;
import
java.util.Collections;
import
java.util.List;
/**
* API layer for persisting and retrieving the Book objects.
*/
public
class
BookDAL {
private
static
BookDAL bookDAL =
new
BookDAL();
public
List<Book> getAllBooks(){
return
Collections.EMPTY_LIST;
}
public
Book getBook(String isbn){
return
null
;
}
public
String addBook(Book book){
return
book.getIsbn();
}
public
String updateBook(Book book){
return
book.getIsbn();
}
public
static
BookDAL getInstance(){
return
bookDAL;
}
}
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当前DAL层以上没有任何功能,我们将对这段代码TDD进行单元测试。DAL层可能与ORM映射API或者数据库API通讯,而我们不关心的这些API是如何设计的。
测试驱动DAL层
对单元测试和Java Mock有很多框架,对这个例子,我将选择JUnit做单元测试,Mockito作为Java mock。我们会在Maven的pom.xml文件中更新依赖属性。
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<
project
xmlns
=
"http://maven.apache.org/POM/4.0.0"
xmlns:xsi
=
"http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation
=
"http://maven.apache.org/POM/4.0.0 <a href="
http://maven.apache.org/maven-v4_0_0.xsd">http://maven.apache.org/maven-v4_0_0.xsd"</
a
>>
<
modelVersion
>4.0.0</
modelVersion
>
<
groupId
>info.sanaulla</
groupId
>
<
artifactId
>MockitoDemo</
artifactId
>
<
packaging
>jar</
packaging
>
<
version
>1.0-SNAPSHOT</
version
>
<
name
>MockitoDemo</
name
>
<
url
>http://maven.apache.org</
url
>
<
dependencies
>
<!-- Dependency for JUnit -->
<
dependency
>
<
groupId
>junit</
groupId
>
<
artifactId
>junit</
artifactId
>
<
version
>4.10</
version
>
<
scope
>test</
scope
>
</
dependency
>
<!-- Dependency for Mockito -->
<
dependency
>
<
groupId
>org.mockito</
groupId
>
<
artifactId
>mockito-all</
artifactId
>
<
version
>1.9.5</
version
>
<
scope
>test</
scope
>
</
dependency
>
</
dependencies
>
</
project
>
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现在进行BookDAL类的单元测试。单元测试中,我们将注入mock数据到BookDAL类,因此我们可以不依赖数据源就可以完成API的测试。
最初我们有一个空的测试类:
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public
class
BookDALTest {
public
void
setUp()
throws
Exception {
}
public
void
testGetAllBooks()
throws
Exception {
}
public
void
testGetBook()
throws
Exception {
}
public
void
testAddBook()
throws
Exception {
}
public
void
testUpdateBook()
throws
Exception {
}
}
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我们将使用下面的setUp()函数把BookDAL类注入mock对象,并设置mock对象数据:
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public
class
BookDALTest {
private
static
BookDAL mockedBookDAL;
private
static
Book book1;
private
static
Book book2;
@BeforeClass
public
static
void
setUp(){
//Create mock object of BookDAL
mockedBookDAL = mock(BookDAL.
class
);
//Create few instances of Book class.
book1 =
new
Book(
"8131721019"
,
"Compilers Principles"
,
Arrays.asList(
"D. Jeffrey Ulman"
,
"Ravi Sethi"
,
"Alfred V. Aho"
,
"Monica S. Lam"
),
"Pearson Education Singapore Pte Ltd"
,
2008
,
1009
,
"BOOK_IMAGE"
);
book2 =
new
Book(
"9788183331630"
,
"Let Us C 13th Edition"
,
Arrays.asList(
"Yashavant Kanetkar"
),
"BPB PUBLICATIONS"
,
2012
,
675
,
"BOOK_IMAGE"
);
//Stubbing the methods of mocked BookDAL with mocked data.
when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2));
when(mockedBookDAL.getBook(
"8131721019"
)).thenReturn(book1);
when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn());
when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn());
}
public
void
testGetAllBooks()
throws
Exception {}
public
void
testGetBook()
throws
Exception {}
public
void
testAddBook()
throws
Exception {}
public
void
testUpdateBook()
throws
Exception {}
}
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在上面的setUp()方法中,我做了
:
1. 创建一个BookDAL的mock对象
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BookDAL mockedBookDAL = mock(BookDAL.
class
);
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2. 存根带mock数据的BookDAL对象的API,这样无论何时调用API都可以返回mock数据。
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//When getAllBooks() is invoked then return the given data and so on for the other methods.
when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2));
when(mockedBookDAL.getBook(
"8131721019"
)).thenReturn(book1);
when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn());
when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn());
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填充剩余的测试方法:
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package
info.sanaulla.dal;
import
info.sanaulla.models.Book;
import
org.junit.BeforeClass;
import
org.junit.Test;
import
static
org.junit.Assert.*;
import
static
org.mockito.Mockito.mock;
import
static
org.mockito.Mockito.when;
import
java.util.Arrays;
import
java.util.List;
public
class
BookDALTest {
private
static
BookDAL mockedBookDAL;
private
static
Book book1;
private
static
Book book2;
@BeforeClass
public
static
void
setUp(){
mockedBookDAL = mock(BookDAL.
class
);
book1 =
new
Book(
"8131721019"
,
"Compilers Principles"
,
Arrays.asList(
"D. Jeffrey Ulman"
,
"Ravi Sethi"
,
"Alfred V. Aho"
,
"Monica S. Lam"
),
"Pearson Education Singapore Pte Ltd"
,
2008
,
1009
,
"BOOK_IMAGE"
);
book2 =
new
Book(
"9788183331630"
,
"Let Us C 13th Edition"
,
Arrays.asList(
"Yashavant Kanetkar"
),
"BPB PUBLICATIONS"
,
2012
,
675
,
"BOOK_IMAGE"
);
when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2));
when(mockedBookDAL.getBook(
"8131721019"
)).thenReturn(book1);
when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn());
when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn());
}
@Test
public
void
testGetAllBooks()
throws
Exception {
List<Book> allBooks = mockedBookDAL.getAllBooks();
assertEquals(
2
, allBooks.size());
Book myBook = allBooks.get(
0
);
assertEquals(
"8131721019"
, myBook.getIsbn());
assertEquals(
"Compilers Principles"
, myBook.getTitle());
assertEquals(
4
, myBook.getAuthors().size());
assertEquals((Integer)
2008
, myBook.getYearOfPublication());
assertEquals((Integer)
1009
, myBook.getNumberOfPages());
assertEquals(
"Pearson Education Singapore Pte Ltd"
, myBook.getPublication());
assertEquals(
"BOOK_IMAGE"
, myBook.getImage());
}
@Test
public
void
testGetBook(){
String isbn =
"8131721019"
;
Book myBook = mockedBookDAL.getBook(isbn);
assertNotNull(myBook);
assertEquals(isbn, myBook.getIsbn());
assertEquals(
"Compilers Principles"
, myBook.getTitle());
assertEquals(
4
, myBook.getAuthors().size());
assertEquals(
"Pearson Education Singapore Pte Ltd"
, myBook.getPublication());
assertEquals((Integer)
2008
, myBook.getYearOfPublication());
assertEquals((Integer)
1009
, myBook.getNumberOfPages());
}
@Test
public
void
testAddBook(){
String isbn = mockedBookDAL.addBook(book1);
assertNotNull(isbn);
assertEquals(book1.getIsbn(), isbn);
}
@Test
public
void
testUpdateBook(){
String isbn = mockedBookDAL.updateBook(book1);
assertNotNull(isbn);
assertEquals(book1.getIsbn(), isbn);
}
}
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使用maven命令: mvn test进行测试。输出如下:
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-------------------------------------------------------
T E S T S
-------------------------------------------------------
Running info.sanaulla.AppTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.029 sec
Running info.sanaulla.dal.BookDALTest
Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.209 sec
Results :
Tests run: 5, Failures: 0, Errors: 0, Skipped: 0
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至此,通过使用mock框架,在不用实际配置数据源的情况下,就可以测试DAL类。
原文链接: dzone 翻译: ImportNew.com - liken译文链接: http://www.importnew.com/10083.html
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